Crank movement eliminating dead center



July 18, 1939. A. B. BROLUSKA 2,166,565

CRANK MOVEMENT ELIMINATING DEAD CENTER FiledNov. 7. 1958 4 Sheets-Sheet1 77 'fnveni or-r y 18, A. B. BROLUSKA I 2,166,565

' CRANK MOVEMENT ELIMINATING .DEAD CENTER Filed Nov. 7, 1938 4Sheets-Sheet 2 M @gm y 8, 1939. A. B. BROLUSKA 2,166,565

CRANK MOVEMENT ELIMINATING DEAD CENTER Filed Nov. 7, 1938 4 Sheets-Sheet25 g I al a .Z'vw-entbr- July 18, 1939. A. B. BROLU SKA CRANK MOVEMENTELIMINATI NG DEAD CENTER Filed Nov. 7, 1958 4 Sheets-Sheet 4 ffzmni qrPatented July 18, 1939 UNI TED STATES CRANK MOVEMENT ELIMINATING DEADCENTER Amel B.-Broluska, Detroit, Mich. Application November 7, 1938,Serial No. 239,239

'7 Claims.

' My invention relates to crank movements for use in machinesof allkinds in which a reciprocatory motion is, converted into a rotary one,and

more particularly adapted for such movements in which the useful work isapplied to the rotary element during travel of the reciprocatory elementin one direction only.

The principal object of my saidinvention is to provide a movement of thecharacter referred to in which the dead-center effect common to ordinarycrank movements is eliminated at the commencement of the working orpower stroke,

so that the dynamic force of the reciprocatory element is transmittedmore effectively to the rotary element, thereby reducing frictionallosses and economising the available power.

Such an object is particularly desirable in the case of pedal-operateddevices such as printing machines, sewing machines, and especially inbicycles which have again become an important feature of thenationallife, and are being manufactured and sold in increasingly large numbers.Its importance as'applied to machines of the class just recited isparticularly great on account of the saving of human power and thereduction of personal fatigue, enabling the operator to concentrate hisattention on the Work being done, and in the case of bicycles to betterenjoy the healthy exercise and the contemplation of the surroundingscenery.

It is contemplated, however that my improved crank movement will befound equally advantageous when used in prime movers such as gas andgasoline engines, Diesel engines and steam engines, as applied to thepropulsion of automobiles, trucks, tractors, airplanes and dirigibles,as well as power boats and other marine and river craft, andalsor-ailway locomotives.

A further object of my said invention is to provide a crank mechanismwhich is simple in construction having regard to its merits andadvantages, and in which the problem of efficient lubrication is solvedin a novel and reliable manner.

With these and other objects in View, I will now describe a preferredembodiment of my invention, reference being had to the accompanying;drawings, in which- Figure 1 is a fragmentary side elevation showing myimproved crank mechanism applied to an ordinary bicycle.

Figure 2 is a fragmentary plan view of the same.

Figure 3 is a fragmentary side elevation corresponding to Figure 1,showing a modification of my crank mechanism.

Figure 4 is a fragmentary plan view of the Same; i

Figure 5is a fragmentary side elevation corresponding to Figure 1,showing a still further modification of my crank mechanism. fl

Figure 6 is a fragmentary plan view of the same.

Figure 'l is a fragmentary vertical section, taken in a plane passingthrough the center line of the crank shaft, showing one form of my im-10 proved crank mechanism as applied to a twocylinder vertical gasolineengine.

Figure 8 is a fragmentary section taken on line 8-3 of Figure 7'.

Figure 9 is a diagram illustrating in a general I! way the operation ofmy improved crank mechanism.

Figure 10 is a fragmentary sectional view showing an improved method oflubrication employed at the connecting points. of the linkages hereindescribed and forming part of my crank mechanism.

Like characters designate corresponding parts throughout the severalviews.

Referring more particularly to'Figures l and 2 5 of the drawings, Idesignates the conventional crank hanger, located as usual at the commonintersection of the front brace II, the center post or saddle supportl2, and the rear fork [3, the bifurcations l3l of which are connected to0 the rear axle of the vehicle in the usual way.

In suitable anti-friction bearings within the crank hanger l issupported a crank shaft 2 upon which is keyed the driving sprocket 3from which the power of the driver is transmitted 3 through the pitchchain 3! to the rearsprocket, not shown, which is connected in drivingrelation with the rear wheel 32. Adjacent the sprocket wheel and securedto the frame as by screws ll, which threadedly engage bosses iiil uponthe said frame, is a plate 4 and to this plate is secured'as by screws5| a cam 5 of the form sometimes described as a triangular excentric,the said camhaving the peculiar property of fitting closely between apair of parallel surfaces upon 45 an element to be moved during itsentire rotation. Thiscam also imparts to the said element a. movementduring one fourth of its rotation and then; allowsthe'element to. restduring another one fourth, after which it gives a'reverse 50 movementduring one fourth, followed by a rest, and so forth in acontinuouscycle.

Keyed to the crank shaft 2 is a crank 6 and arranged at an angle to thesaid crank is a pedal arm 1: upon which .is. rotatably mounted. a pedal55 II having preferably rubber portions I2 and a central axle 13. Thepedal arm I has connected to it as by pivots I6, I6 the links I4, Iwhich constitute, in combination with the pedal arm I, a rigidtriangular structure, and the pedal arm is further connected by means ofthe link 11 and the pivot II to the extreme end of the crank 6. In thismanner the pedal arm I is coupled to the crank 6 by a linkage whichpermits of a certain amount of movement of the said arm in relation tothe crank, and the said arm is provided with an opening I8 which ispartly defined by a pair of parallel surfaces I8, these surfaces beingspaced apart so that they are maintained in operative relation with thecam 5 at all times.

Thus, it will be seen that as the armI is rotated by pressure of theoperator upon the pedal I I, the effective radius of the pedal isgradually changed during such rotation and the fixed cam 5 is sopositioned upon the frame that the pedal is pushed in a forwarddirection from the center line :s-ar of the crank hanger just when itpasses the said center line, by which means the usual dead center effectof the common crank movement is avoided and the leverage of the pedal isincreased at the critical moment when the foot of the operator is in theposition to do the maximum amount of work.

The description of my improved mechanism so far relates only to thepedal mechanism on the left side of the operator. It will be understood,however, that the crank mechanism upon the right hand of the operator issimilarly constructed with the exception that, since there is nosprocket on this side, the cam 5 is keyed directly upon the outerperiphery of the crank hanger itself, thereby dispensing with the fixedplate 4 above referred to. With this exception the parts upon the righthand are similar in all respects to that above described, the variouselements being similarly designated. For the sake of clearness, however,the parts upon the right hand are omitted from the elevationalview,'Figure 1.

Referring now to Figures 3 and 4 of the drawings, the pedal arm I isconnected directly as by the pivot 76" to the crank 6, and instead ofthe cam 5 described and shown in Figures 1 and 2, there is provided anexcentric 8 which is fastened to the plate 4 as by the screws 8| and issurrounded by an excentric strap 82, made in two halves and securedtogether as by the screws 83. The strap 82 is connectedby a short arm 84to the pedal arm I as by the pivot 85 so that the effective radius ofthe pedal is increased during the upper part of the forward rotation inthe same manner as is obtained by the cam previously described. Theexcentric strap 82 is provided with an oil container 86 closed by ascrew cap 81.

In Figures 5 and 6 of the drawings I have shown a still furthermodification of my improved crank mechanism in which the pedal arm I isreinforced by members I, I" as shown, so as to provide a triangularbrace structure of great rigidity. The pedal arm I in this case isconnected directly by the pivot 16" to the crank 6, the latter being inthis case provided with an extension 6| which is arranged at an angle tothe main portion, as shown. With this exception the arrangement issubstantially the same as shown in Figures 3 and 4, the excentric 8 andstrap 82 being employed for producing the off center movement of thepedal during the upper portion of its forward stroke. It will be notedthat in Figures 5 and 6 the right hand pedal mechanism only is shown,the left hand elements being omitted for the sake of clearness.

In Figures 7 and 8 of the drawings A designates the cylinder block of atwo-cylinder fourstroke cycle internal combustion engine, the said blockbeing provided with a head B of ordinary construction and also with acrank case C. D are the compression spaces and E the cylinder bores inwhich operate pistons F coupled by the usual connecting rods G and wristpins H to the crank pins K. Within the crank case 0, which is splitdiametrically, as indicated at C, are bearings L of conventionalconstruction within which rotate the various sections of the crank shaft2.

The operative elements of the crank mechanism in this application aresubstantially the same as shown in Figure 1 applied to a bicycle. theseveral parts being similarly designated. In this case, however, thecams 5 which are arrangedin cooperative relation with the arms I areformed integral with bushings L, the said bushings being prevented fromrotating within the bearings L as by dowel pins L3 and being providedwith oil-ways L4. The conventional working parts of the engine such asthe valves D .and valve rods D2, cam shaft D3, and tappets D4 need nofurther description since they form no part of the present invention.

In thorough diagram shown in Figure 9 of the drawings I have endeavoredto give a general idea of the manner in which my improved crankmechanism obviates the usual dead center condition. Thus by the actionof the cam 5 upon the member I the crank K which corresponds to thepedal axis in the case of the bicycle application is moved forwardapproximately fifteen degrees from the vertical center line which wouldotherwise be occupied by the crank of ordinary construction. The wordscrank circle indicate the circle around which the crank 6 passes whilethe words pedal circle show the total movement of the pedal, whichamounts to one hundred and ninety-five degrees at the same time that thecrank pin K moves through one hundred and eighty degrees. In this mannerthe purchase or leverage of the crank pin K is increased by fifteendegrees at the moment when the maximum power is exerted by the foot ofthe operator in the case of a bicycle, or by the connecting rod in thecase of the motor shown in Figures 7 and 8.

In the fragmentary drawings, Figure 10, I have illustrated a novel andeffective method of lubricating the pivots which connect the variousmembers and links of the mechanisms herein shown and described. Thus thepivot pin designated "I6 is secured in the member I5 by a tight ordriven fit and welded in position as indicated at I6 The portion I6 isrotatable in the member I4 and is provided with a head I6 and in orderto provide for lubrication of this journal, there may be employed an oilfitting of the Alemite type which is arranged to deliver lubricant intoan opening It so as to provide effective lubrication of the bearing.

It will be observed from the foregoing description and by reference tothe drawings that I have devised a highly efficient crank movement bywhich the maximum percentage of the energy input is converted intodynamic effect upon the various instrumentalities to be operated, andwhile I have herein described and shown a preferred embodiment of myinvention, it will be readily understood by those skilled in the art towhich the same pertains that various changes in detail may be madewithout departing from the spirit of my invention as defined in theappended claims.

Having thus described my said invention, what I claim and desire tosecure by Letters Patent of the United States is:

1. In a crank movement, the combination, with a fixed bearing, of adriven shaft rotatably mounted in said bearing, a driven crank securedupon said shaft, a cam-like member fixed upon I said bearing, a drivingarm having at one end a crank pin and at the other end a pivot, a linkconnecting said pivot in angularly rearward driving relation with saiddriven crank, and an opening in said driving arm intermediate said crankpin and said pivot adapted to slidably engage said cam-like member,whereby said crank pin is advanced beyond the dead center during thecommencement of its forward stroke.

2. In a crank movement, the combination, with a fixed bearing, of adriven shaft rotatably mounted in said bearing, a driven crank securedupon said shaft, a cam-like member fixed upon said bearing, a drivingarm having at one end a crank pin and at the other end a pivot, a linkconnecting said pivot in angularly rearward driving relation with saiddriven crank, and an opening in said driving arm intermediate said crankpin and said pivot defined by two faces arranged in parallel spacedrelation and adapted to slidably engage said cam-like member, wherebysaid crank pin is advanced beyond the dead center during thecommencement of its forward stroke.

3. In a crank movement, the combination, with a fixed bearing, of adriven shaft rotatably mounted in said bearing, a driven crank securedupon said shaft, 21. triangularv cam-like member fixed upon saidbearing, a driving arm having at one end a crank pin and at the otherend a pivot, a link connecting said pivot in angularly rearward drivingrelation with said driven crank, and an opening in said driving armintermediate said crank pin and said pivot defined by two faces arrangedin parallel spaced relation and adapted to slidably engage said cam-likemember, whereby said crank pin is advanced beyond the dead center duringthe commencement of its forward stroke.

4. In a crank movement, the combination, with a fixed bearing, of adriven shaft rotatably mounted in said bearing, a driven crank securedupon said shaft, an eccentric member fixed upon said bearing, a drivingarm having at one end a crank pin and having the other end pivoted tosaid driven crank, and a strap upon said eccentric member pivoted tosaid driving arm intermediate its ends, whereby said crank pin isadvanced beyond the dead center during the commencement of its forwardstroke.

5. In a crank movement, the combination, with a bicycle frame, of afixed bearing upon said frame, a shaft rotatably mounted in saidbearing, a pair of driven cranks fixed upon said shaft in diametricallyopposed relation, a road wheel upon said frame connected by gearing withsaid shaft, a pair of cam-like members fixed upon said frame, a pair ofdriving arms each having at one end a foot pedal and at the other end apivot, and links connecting said respective pivots to said drivencranks, there being openings in said driving arms adapted to slidablyengage said respective cam-like members, whereby said pedals areadvanced beyond their dead centers during the commencement of theirforward strokes.

6. In a crank movement, the combination, with a fixed bearing, of adriven shaft rotatably mounted in said bearing, a driven crank securedupon said shaft, a cam-like member fixed upon said bearing, asubstantially triangular driving structure having at one apex a crankpin and at the opposed apex a pivot, a link connecting said pivot inangularly rearward driving relation with said driven crank, and anopening in said structure intermediate said crank pin and said pivotadapted to'slidably engage said cam-like member, whereby said crank pinis advanced beyond the dead center during the commencement of itsforward stroke, so that a higher degree of leverage is obtained on theworking stroke and a lower degree on the idling stroke and a greaterproportion of the dynamic force exerted is utilized in the performanceof useful work 7. In a crank movement,the combination, with a fixedbearing, of a driven shaft rotatably mounted in saidbearing, a drivencrank secured upon said shaft, a triangular cam-like member fixed uponsaid bearing, a substantially triangular driving structure having at oneapex a crank pin and at the opposed apex a pivot, a link connecting saidpivot in angularly rearward driving relation with said driven crank, andan opening in said structure intermediate said crank pin and said pivotadapted to slidably engage said cam-like member, whereby said crank pinis advanced beyond the dead center during the commencement of itsforward stroke, so that a higher degree of leverage is obtained on theworking stroke and a lower degree on the idling stroke and a greaterproportion of the dynamic force exerted is utilized in the performanceof useful work.

AMEL B. BROLUSKA.

